Polyvinyl pyrrolidone (PVP) and some related polymers are known ingredients of laundry detergent compositions, providing the benefit of reduced dye transfer between fabrics in a mixed load.
Laundry detergent compositions containing PVP as a dye transfer inhibitor are disclosed, for example, in WO 92 18597A and WO 95 27028A (Procter & Gamble).
GB 1 354 498 (Unilever) discloses laundry detergent compositions containing vinyl pyrrolidone/vinyl acetate (PVP/VA) random copolymers as antiredeposition agents. PVP itself is stated to be ineffective.
Other vinyl pyrrolidone copolymers are known for cosmetic and agricultural applications.
Definition of the Invention
In a first aspect, the present invention provides a laundry detergent composition comprising an organic surfactant, and a hydrophobically modified vinyl pyrrolidone polymer which is a copolymer having a vinyl pyrrolidone backbone and pendant hydrophobic side chains comprising alkyl chains containing from 4 to 20 carbon atoms, the polymer being present in an amount effective to improve detergency and/or antiredeposition.
In a second aspect, the invention provides the use of a hydrophobically modified vinyl pyrrolidone polymer to improve the detergency and/or antiredeposition of a laundry detergent composition.
The Hydrophobically Modified Vinyl Pyrrolidone Polymer
The polymer used in the detergent compositions of the invention is a polyvinyl pyrrolidone modified by the inclusion of hydrophobic units as pendant side chains. The polymer is a copolymer of vinyl pyrrolidone (VP), providing the polymer backbone, and a hydrophobic monomer.
Vinyl pyrrolidone has the formula

The hydrophobic side chains preferably comprise alkyl chains containing from 4 to 20 carbon atoms.
First Preferred Embodiment
According to a first preferred embodiment of the invention, the polymer is an alkylated vinyl pyrrolidone polymer wherein the alkyl chains contain from 4 to 20 carbon atoms.
In this embodiment of the invention, the hydrophobic side chains are derived from a hydrophobic comonomer which is an olefin containing from 4 to 20 carbon atoms.
Preferably the polymer contains from 10 to 90 mole % of vinyl pyrrolidone (VP) units and from 10 to 90 mole % of hydrophobic comonomer units.
Suitable polymers are commercially available from International Specialty Products (ISP) as the Ganex (Trade Mark), Antaron (Trade Mark) and Agrimer (Trade Mark) series. They may be prepared by chemical modification of PVP with long-chain alpha-olefins. Examples are shown in the Table below.
Polymer tradeAlkylComonomerMole ratioPhysicalnamechain(olefin)VP:olefinformAgrimer AL-10C4Butene90:10Water-Ganex P904LCsolubleAntaron P904powderGanex V216C16Hexadecene20:80Water-Antaron V216insolublewaxGanex V516C16Hexadecene50:50Water-Antaron V516insolublewax
These polymers are marketed for use in cosmetic and personal care compositions, and for agricultural purposes as ingredients in crop treatment compositions.
Second Preferred Embodiment
According to a second preferred embodiment of the invention, the hydrophobically modified vinyl pyrrolidone polymer has pendant hydrophobic side chains which are alkyl chains having from 4 to 20 carbon atoms linked to the vinyl pyrrolidone backbone by an ester linkage.
The hydrophobic monomer precursor of the side chains is preferably a vinyl ester of the general formula I:R1—CO—O—CH═CH2  (I)wherein R1 is a linear or branched alkyl group having from 4 to 16 carbon atoms.
In the general formula I, R1 is preferably a linear or branched alkyl group having from 6 to 10 carbon atoms.
More preferably, R1 is a group of the formula II
wherein R2 is a linear alkyl group having from 2 to 8 carbon atoms and R3 is a methyl or ethyl group.
Most preferably, the hydrophobic comonomer of the formula I is vinyl 2-ethylhexanoate:

The polymer preferably contains from 90 to 99.5 wt % of vinyl pyrrolidone monomer units and from 0.5 to 10 wt % of vinyl 2-ethyl hexanoate monomer units.
Copolymers of vinyl pyrrolidone and vinyl 2-ethylhexanoate have the general formula III
Preparation of the Polymers having an Ester Linkage
These polymers may be prepared by free radical polymerisation.
A process suitable for preparing these polymers is disclosed in U.S. Pat. No. 5,319,041 (Zhong et al) which describes the synthesis of copolymers of vinylpyrrolidone and vinyl acetate. An alternative process is disclosed in U.S. Pat. No. 5,122,582 (Porthoff-Karl).
The Laundry Detergent Composition
In the detergent composition of the invention, the polymer is present in an amount sufficient to enhance detergency and/or antiredeposition. Suitably the polymer is present in an amount of from from 0.5 to 5 wt %, preferably from 1 to 4 wt %.
The detergent composition may suitably comprise:
(a) from 5 to 60 wt %, preferably from 10 to 40 wt %, of organic surfactant,
(b) optionally from 5 to 80 wt %, preferably from 10 to 60 wt %, of detergency builder,
(c) from 0.5 to 5 wt %, preferably from 1 to 4 wt %, of the hydrophobically modified vinyl pyrrolidone polymer,
(d) optionally other detergent ingredients to 100 wt %.
The pH of the detergent composition is suitably in the range of from 7.0 to 11.0, preferably 7.5 to 10.5. During the wash in dilute form the pH of the detergent composition is from 7 to 11, preferably from 8.0 to 10.5.
The Organic Surfactant
The compositions of the invention may contain any organic surfactants (detergent-active compounds) suitable for incorporation into laundry detergent compositions.
Detergent-active compounds (surfactants) may be chosen from soap and non-soap anionic, cationic, nonionic, amphoteric and zwitterionic detergent-active compounds, and mixtures thereof. Many suitable detergent-active compounds are available and are fully described in the literature, for example, in “Surface-Active Agents and Detergents”, Volumes I and II, by Schwartz, Perry and Berch. The preferred detergent-active compounds that can be used are soaps and synthetic non-soap anionic and nonionic compounds. The total amount of surfactant present is suitably within the range of from 5 to 60 wt %, preferably from 5 to 40 wt %.
Anionic surfactants are well-known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly linear alkylbenzene sulphonaites having an alkyl chain length of C8–C15; primary and secondary alkylsulphates, particularly C8–C20 primary alkyl sulphates; alkyl ether sulphates; olefin sulphonates; alkyl xylene sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates. Sodium salts are generally preferred. Nonionic surfactants that may be used include the primary and secondary alcohol ethoxylates, especially the C8–C20 aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C10–C15 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Non-ethoxylated nonionic surfactants include alkylpolyglycosides, glycerol monoethers, and polyhydroxyamides (glucamide).
Cationic surfactants that may be used include quaternary ammonium salts of the general formula R1R2R3R4N+X− wherein the R groups are long or short hydrocarbyl chains, typically alkyl, hydroxyalkyl or ethoxylated alkyl groups, and X is a solubilising anion (for example, compounds in which R1 is a C8–C22 alkyl group, preferably a C8–C10 or C12–C14 alkyl group, R2 is a methyl group, and R3 and R4, which may be the same or different, are methyl or hydroxyethyl groups); and cationic esters (for example, choline esters).
According to a preferred embodiment of the invention, the composition comprises a sulphonate anionic surfactant. According to an especially preferred embodiment, the sulphonate anionic surfactant comprises linear alkylbenzene sulphonate (LAS).
An especially favourable interaction between LAS and the hydrophobically modified vinyl pyrrolidone polymer has been observed, giving improved primary detergency on difficult oily and particulate soils such as dirty motor oil and mud, and reduced redeposition of soil onto the washload during the wash (sometimes referred to as secondary detergency). Without being bound by theory, it is postulated that the this benefit may be attributed to a reduction in the critical micelle concentration (CMC) of the LAS. Preferably, the compositions contains from 3 to 30 wt %, more preferably from 10 to 25 wt %, of LAS.
The Optional Detergency Builder
Preferably, the detergent compositions of the invention also contain one or more detergency builders. The total amount of detergency builder in the compositions may suitably range from 5 to 80 wt %, preferably from 10 to 60 wt %.
Preferred builders are alkali metal aluminosilicates, more especially crystalline alkali metal aluminosilicates (zeolites), preferably in sodium salt form.
Zeolite builders may suitably be present in a total amount of from 5 to 60 wt %, preferably from 10 to 50 wt %.
The zeolites may be supplemented by other inorganic builders, for example, amorphous aluminosilicates, or layered silicates such as SKS-6 ex Clariant.
The zeolites may be supplemented by organic builders, for example, polycarboxylate polymers such as polyacrylates and acrylic/maleic copolymers; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-, di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates, hydroxyethyliminodiacetates, alkyl- and alkenylmalonates and succinates; and sulphonated fatty acid salts.
Alternatively, the compositions of the invention may contain phosphate builders, for example, sodium tripolyphosphate.
Especially preferred organic builders are citrates, suitably used in amounts of from 1 to 30 wt %, preferably from 2 to 15 wt %; and acrylic polymers, more especially acrylic/maleic copolymers, suitably used in amounts of from 0.5 to 15 wt %, preferably from 1 to 10 wt %. Builders, both inorganic and organic, are preferably present in alkali metal salt, especially sodium salt, form.
According to a preferred embodiment of the invention, the detergency builder, which is present in an amount of from 5 to 80 wt %, preferably from 10 to 60 wt %, is selected from sodium tripolyphosphate, zeolites, sodium carbonate and mixtures thereof.
Other Detergent Ingredients
Detergent compositions according to the invention may also suitably contain a bleach system. Preferably this will include a peroxy bleach compound, for example, an inorganic persalt or an organic peroxyacid, capable of yielding hydrogen peroxide in aqueous solution.
Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate, the latter being especially preferred. The sodium percarbonate may have a protective coating against destabilisation by moisture. The peroxy bleach compound is suitably present in an amount of from 5 to 35 wt %, preferably from 10 to 25 wt %.
The peroxy bleach compound may be used in conjunction with a bleach activator (bleach precursor) to improve bleaching action at low wash temperatures. The bleach precursor is suitably present in an amount of from 1 to 8 wt %, preferably from 2 to 5 wt %. Preferred bleach precursors are peroxycarboxylic acid precursors, more especially peracetic acid precursors and peroxybenzoic acid precursors; and peroxycarbonic acid precursors. An especially preferred bleach precursor suitable for use in the present invention is N,N,N′,N′-tetracetyl ethylenediamine (TAED).
A bleach stabiliser (heavy metal sequestrant) may also be present. Suitable bleach stabilisers include ethylenediamine tetraacetate (EDTA), diethylenetriamine pentaacetate (DTPA), ethylenediamine disuccinate (EDDS), and the polyphosphonates such as the Dequests (Trade Mark), ethylenediamine tetramethylene phosphonate (EDTMP) and diethylenetriamine pentamethylene phosphate (DETPMP).
The compositions of the invention may contain alkali metal, preferably sodium, carbonate, in order to increase detergency and ease processing. Sodium carbonate may suitably be present in amounts ranging from 1 to 60 wt %, preferably from 2 to 40 wt %.
As previously indicated, sodium silicate may also be present. The amount of sodium silicate may suitably range from 0.1 to 5 wt %. Sodium silicate, as previously indicated, is preferably introduced via the second base granule.
Powder flow may be improved by the incorporation of a small amount of a powder structurant. Examples of powder structurants, some of which may play other roles in the formulation as previously indicated, include, for example, fatty acids (or fatty acid soaps), sugars, acrylate or acrylate/maleate polymers, sodium silicate, and dicarboxylic acids (for example, Sokalan (Trade Mark) DCS ex BASF). One preferred powder structurant is fatty acid soap, suitably present in an amount of from 1 to 5 wt %.
Other materials that may be present in detergent compositions of the invention include antiredeposition agents such as cellulosic polymers; soil release agents; anti-dye-transfer agents; fluorescers; inorganic salts such as sodium sulphate; enzymes (proteases, lipases, amylases, cellulases); dyes; coloured speckles; perfumes; and fabric conditioning compounds. This list is not intended to be exhaustive.
Product Form and Preparation
The compositions of the invention may be of any suitable physical form, for example, particulates (powders, granules, tablets), liquids, pastes, gels or bars.
According to one especially preferred embodiment of the invention, the detergent composition is in particulate form.
Powders of low to moderate bulk density may be prepared by spray-drying a slurry, and optionally postdosing (dry-mixing) further ingredients. “Concentrated” or “compact” powders may be prepared by mixing and granulating processes, for example, using a high-speed mixer/granulator, or other non-tower processes.
Tablets may be prepared by compacting powders, especially “concentrated” powders.
Also preferred are liquid detergent compositions, which may be prepared by admixing the essential and optional ingredients in any desired order to provide compositions containing the ingredients in the requisite concentrations.
Incorporation of the Hydrophobically Modified Vinyl Pyrrolidone Polymer
The polymers may be incorporated at any suitable stage in the manufacture of the compositions of the invention.
For example, in the manufacture of spray-dried particulate compositions, polymer in powder or solution (preferably aqueous) form may be incorporated in the slurry. For non-tower particulates, polymer powder or solution may be easily introduced into mixing and granulating apparatus, either alone or in admixture with other solid or liquid ingredients as appropriate.